Magneto-optic recording medium.

摘要

A magneto-optic recording medium which is comprised of a first, a second, a third and a fourth magnetic layers coupled each other between the adjacent layers by an exchange force, wherein said first through fourth magnetic layers satisfy Tc1<Tc2, Tc3<Tc2, Tc1<Tc4 and Tc3<Tc4 in relation to respective Curie points and satisfy the following conditions at room temperature; (1) the direction of sublattice magnetizations of the transition metal (TM) of the third and fourth magnetic layers is coincident with each other in the initializing magnetic field, (2) a magnetic field necessary for changing the direction of sublattice magnetization of TM of the first magnetic layer from the state where it is coincident with that of the second magnetic layer to the state where it is reverse to that of the second magnetic layer when the direction of sublattice magnetization of TM of the second magnetic layer is reverse to that of the third and fourth magnetic layers is larger than a magnetic field necessary for changing the direction of sublattice magnetization of TM of the second magnetic layer from the state where it is coincident with that of the first magnetic layer to the state where it is reverse to that of the first magnetic layer when the direction of sublattice magnetization of TM of the first magnetic layer is reverse to that of the third and fourth magnetic layers, (3) the magnetization of the fourth magnetic layer is not inverted during recording and reproducing, and (4) the magnetization of the first magnetic layer is not inverted by the inversion of the magnetization of the second magnetic layer.